In recent years, energy efficient, environmentally friendly industries are highlighted, and thus various studies are in progress to solve both the energy and environmental problems all over the world.
In particular, technologies for insulation materials are being tried in various ways, in order to reduce the power consumption of refrigerators, and in order to save energy in buildings, in terms of global warming.
Refrigerators consume high power consumption from among consumer electronics products, and thus energy consumption reduction of the refrigerators is indispensable in global warming situations. The power consumption of the refrigerators is determined mostly by the efficiency of compressors for cooling and the heat insulation performance of insulation materials related to heat leakage.
In addition, insulation materials such as mineral wool and polyurethane have been traditionally used as insulation materials for energy savings in buildings. Recently, VIP (Vacuum Insulation Panel), and aerogels are attracting attention, and VIM (Vacuum Insulation Material), DIM (Dynamic Insulation Material) and the like have been studied in future technologies.
VIP and aerogels each having very low heat conductivity may reduce the energy consumption compared to conventional heat insulation materials, and thus have advantages of remarkably expanding a living area. In particular, since the airgel can be made of a translucent and transparent material, the airgel has a very large possibility of being applied to buildings.
Korean Patent Application Publication No. 10-2011-77859 has proposed a vacuum heat insulation material including: a core portion including a core material; and an outer shell material covering the core portion in which and which the core portion is formed under a reduced pressure, wherein the outer shell material is at least one non-woven layer. In this case, the core material of the vacuum insulation material may use glass fiber, polyurethane, polyester, polypropylene or polyethylene, but the pore size of the inner portion of glass fiber aggregates does not have a size suitable for trapping air, exhibiting low heat insulation efficiency. Accordingly, glass fibers may cause problems such as a complex and difficult manufacturing process.
Korean Patent Application Publication No. 10-2011-15326 has proposed a core which is located inside an outer shell of a vacuum insulation material, in which the core is obtained by thermally fusing synthetic resin fibers and bonding the thermally fused synthetic resin fibers to each other. However, since the synthetic resin fibers are heated at a temperature of about a melting point and thermally fused to each other, the synthetic resin fibers become a substantially pore-free non-pore state, to thus have a limit to improve the heat insulation efficiency.
Therefore, the present inventors continue to research to improve heat insulation efficiency and invent and derive structural features of a heat insulation sheet to maximize the heat insulation efficiency, to thereby complete an energy-saving, environment-friendly, more economical, utilizable, and competitive heat insulation sheet according to the present invention.